KeyError when faceting along time dimensions

[malmans2]

What happened:
I think the latest pandas (1.1.0) conflicts with faceting along time dimensions.

Minimal Complete Verifiable Example:

import xarray as xr
airtemps = xr.tutorial.open_dataset("air_temperature") 
airtemps['air'].isel(time=slice(2)).plot(col='time') 

This returns the following error:

KeyError: 1356998400000000000

Environment:

Output of xr.show_versions()

INSTALLED VERSIONS

commit: None
python: 3.7.8 | packaged by conda-forge | (default, Jul 31 2020, 02:25:08)
[GCC 7.5.0]
python-bits: 64
OS: Linux
OS-release: 5.4.0-42-generic
machine: x86_64
processor: x86_64
byteorder: little
LC_ALL: None
LANG: en_US.UTF-8
LOCALE: en_US.UTF-8
libhdf5: 1.10.6
libnetcdf: 4.7.4

xarray: 0.16.0
pandas: 1.1.0
numpy: 1.19.1
scipy: 1.5.2
netCDF4: 1.5.4
pydap: None
h5netcdf: None
h5py: None
Nio: None
zarr: 2.4.0
cftime: 1.2.1
nc_time_axis: None
PseudoNetCDF: None
rasterio: None
cfgrib: None
iris: None
bottleneck: 1.3.2
dask: 2.22.0
distributed: 2.22.0
matplotlib: 3.3.0
cartopy: 0.18.0
seaborn: None
numbagg: None
pint: None
setuptools: 49.2.1.post20200802
pip: 20.2.1
conda: None
pytest: 6.0.1
IPython: 7.17.0
sphinx: None

[malmans2]

Here is the full error:

---------------------------------------------------------------------------
KeyError                                  Traceback (most recent call last)
<ipython-input-9-c00f9ae5bb67> in <module>
----> 1 airtemps['air'].isel(time=slice(2)).plot(col='time')

~/anaconda3/envs/ospy_tests/lib/python3.7/site-packages/xarray/plot/plot.py in __call__(self, **kwargs)
    444 
    445     def __call__(self, **kwargs):
--> 446         return plot(self._da, **kwargs)
    447 
    448     # we can't use functools.wraps here since that also modifies the name / qualname

~/anaconda3/envs/ospy_tests/lib/python3.7/site-packages/xarray/plot/plot.py in plot(darray, row, col, col_wrap, ax, hue, rtol, subplot_kws, **kwargs)
    198     kwargs["ax"] = ax
    199 
--> 200     return plotfunc(darray, **kwargs)
    201 
    202 

~/anaconda3/envs/ospy_tests/lib/python3.7/site-packages/xarray/plot/plot.py in newplotfunc(darray, x, y, figsize, size, aspect, ax, row, col, col_wrap, xincrease, yincrease, add_colorbar, add_labels, vmin, vmax, cmap, center, robust, extend, levels, infer_intervals, colors, subplot_kws, cbar_ax, cbar_kwargs, xscale, yscale, xticks, yticks, xlim, ylim, norm, **kwargs)
    636             # Need the decorated plotting function
    637             allargs["plotfunc"] = globals()[plotfunc.__name__]
--> 638             return _easy_facetgrid(darray, kind="dataarray", **allargs)
    639 
    640         plt = import_matplotlib_pyplot()

~/anaconda3/envs/ospy_tests/lib/python3.7/site-packages/xarray/plot/facetgrid.py in _easy_facetgrid(data, plotfunc, kind, x, y, row, col, col_wrap, sharex, sharey, aspect, size, subplot_kws, ax, figsize, **kwargs)
    642 
    643     if kind == "dataarray":
--> 644         return g.map_dataarray(plotfunc, x, y, **kwargs)
    645 
    646     if kind == "dataset":

~/anaconda3/envs/ospy_tests/lib/python3.7/site-packages/xarray/plot/facetgrid.py in map_dataarray(self, func, x, y, **kwargs)
    263         # Get x, y labels for the first subplot
    264         x, y = _infer_xy_labels(
--> 265             darray=self.data.loc[self.name_dicts.flat[0]],
    266             x=x,
    267             y=y,

~/anaconda3/envs/ospy_tests/lib/python3.7/site-packages/xarray/core/dataarray.py in __getitem__(self, key)
    196             labels = indexing.expanded_indexer(key, self.data_array.ndim)
    197             key = dict(zip(self.data_array.dims, labels))
--> 198         return self.data_array.sel(**key)
    199 
    200     def __setitem__(self, key, value) -> None:

~/anaconda3/envs/ospy_tests/lib/python3.7/site-packages/xarray/core/dataarray.py in sel(self, indexers, method, tolerance, drop, **indexers_kwargs)
   1152             method=method,
   1153             tolerance=tolerance,
-> 1154             **indexers_kwargs,
   1155         )
   1156         return self._from_temp_dataset(ds)

~/anaconda3/envs/ospy_tests/lib/python3.7/site-packages/xarray/core/dataset.py in sel(self, indexers, method, tolerance, drop, **indexers_kwargs)
   2100         indexers = either_dict_or_kwargs(indexers, indexers_kwargs, "sel")
   2101         pos_indexers, new_indexes = remap_label_indexers(
-> 2102             self, indexers=indexers, method=method, tolerance=tolerance
   2103         )
   2104         result = self.isel(indexers=pos_indexers, drop=drop)

~/anaconda3/envs/ospy_tests/lib/python3.7/site-packages/xarray/core/coordinates.py in remap_label_indexers(obj, indexers, method, tolerance, **indexers_kwargs)
    395 
    396     pos_indexers, new_indexes = indexing.remap_label_indexers(
--> 397         obj, v_indexers, method=method, tolerance=tolerance
    398     )
    399     # attach indexer's coordinate to pos_indexers

~/anaconda3/envs/ospy_tests/lib/python3.7/site-packages/xarray/core/indexing.py in remap_label_indexers(data_obj, indexers, method, tolerance)
    268             coords_dtype = data_obj.coords[dim].dtype
    269             label = maybe_cast_to_coords_dtype(label, coords_dtype)
--> 270             idxr, new_idx = convert_label_indexer(index, label, dim, method, tolerance)
    271             pos_indexers[dim] = idxr
    272             if new_idx is not None:

~/anaconda3/envs/ospy_tests/lib/python3.7/site-packages/xarray/core/indexing.py in convert_label_indexer(index, label, index_name, method, tolerance)
    188             else:
    189                 indexer = index.get_loc(
--> 190                     label.item(), method=method, tolerance=tolerance
    191                 )
    192         elif label.dtype.kind == "b":

~/anaconda3/envs/ospy_tests/lib/python3.7/site-packages/pandas/core/indexes/datetimes.py in get_loc(self, key, method, tolerance)
    620         else:
    621             # unrecognized type
--> 622             raise KeyError(key)
    623 
    624         try:

KeyError: 1356998400000000000

[keewis]

Thanks for the report, @malmans2. This is a general issue with sel / loc with datetime dtypes, see #4283 and #4292; we're working on this. Unfortunately, our test coverage was not complete enough for us to catch that before the pandas release.

For now, you might want to pin pandas to pandas<1.1.0.

[malmans2]

Got it! Thanks @keewis.

[dcherian]

Closing as duplicate. Thanks @malmans2 for reporting.